Chusetts



Patented Apr. 25, 1922. ELg.1. l

PlsToN PACKING. APPLI'CATION FILED \UG.25, l9l9.

I l I .ii/ml llllfl Flg- K.

L. C. MARSHALL {l} Il I I lulu hu.

UNITED sTATps PATENT ori-"ICEA LEWIS C. MARSHALL, OF WALPOLE, MASSACHUSETTS, ASSIGNOR TO PRESSURE PROOF PISTON RNG COMPANY, Ol BOSTON, vASSACHUSETIS, A CORPORATION OF MASSA..

CHUSETTS.

PISTON PACKING.

Application filed August 25, 1919.

To all whom t may concern J Be it known that I, .nin/rs C. MARSHALL, a citizen of the United States, and resident of lalpole, in the county ot Norfolk and State 0i. Massachusetts, have invented new and useful lfmprovenients in Piston Packings, ot which the following is a specification.

This invention relates to piston packings and while adapted to the packing oilf pistons generally, it is especially designed for the packing of pistons olf internal combustion engines. ln such engines in operation the cylinder is cooled while the piston is hot and the latter' therefore expands more than the cylinder and must litloosely within the cylinder to avoid binding. in order to maintain the high compression which is necessary, the piston is provided with packing rings which not only must lit tightly against the cylinder wall, but must make a tight joint with the grooves ot the piston Within which they are'positioned, to prevent leakage underneath the piston rings. rlhe rings should also be so constructed that they are pressed evenly throughout their circumterential surface against the cylinder wall to avoid an uneven wearingdovvn ot the rings or an uneven wearing o the cylinder which would tend to make the bore of the cylinder unsymmetrical.

The principal object ot the present invention is to provide a novel and improved metallic piston packing which shall accomplish these results and which shall also be simple in construction and tree trom multiplicity of parts and complexity ot construction.

' ln the accompanying drawings which illustrate an embodiment of the inventioin* Figure l is aside elevation of the packing rings in place on a piston head;

. Figure 2 is a sectional view of said packing rings inlplace on a piston head; n

Figure 3 is an enlarged detail view 'in cross-section, illustrating the 'torni ot paolo ing ringss'hown in Figs. l and 2;

.ll`igure -l is an enlarged detail view in cross-section, illusti-atingv a niodil'iration ol the struc-ture shown in ll`ig'. B;

lligure 5 is an enlarged detail 'view in crossseetion, illustrating a still further niodication;

.Figure G .is :i view showing cross-section ol different 'lornis ot steel expander ring which may be employed; and

Specification of Letters Patent.

Patented Apr. 25, 1922.

Serial No. 319,749.

Figure 7 is a perspective view of the three rings which constitute the packing shown in Fig. 5.

Referring to Figures l, 2 and 3 of the drawings, l represents a packing ring divided at a single point 2, but otherwise continuous, and preferably made of grey cast .iron or other suitable material. This ring is triangular in cross-section as shown in Fig. 3, having its peripheral tace 3 disposed at right angles to its tace 4l, and is preferably ot the same external diameter as the cylinder bore. rlhe inner tace 5 ot' the ring l is beveled with respeetto the peripheral tace 3 at an angle, ior example, or' about 400. A sec* ond ring 6 ot cast `iron or other suitable material. is provided having a t-rapeziform cross-section, the outer face 7v of which is beveled at the saine. angle as the beveled face 5 of the ring l and is adapted to rest against lace 5. The ring (3 is divided at only one point and is preferably so lormed as to exert a slight pressure against the inner tace ot ring l, although .it desired the ring` may be so Yformed as to be inert. The position of the rings l and G when assembled is best shown in Figs. 2 and The spring ring 8 is a loro ing or lollowor ring preferably ot spring steel, divided at a single point and normally tending to urge the ring l outwardly against the cylinder wall and upwardly against the upper wall ot the cylinder groove. The ring 8 rests upon the upper vtace ot' the ring G in c ntact with the central portion ot the inner beveled tace 5 ot the ring l. By so positioning the follower ring 8 that its expansive pressure is directed against the ring l in the region oit its middle, the ring l .is urged more evenly against the wall of the cylinder and the wear is more evenly distributed to its peripheral surface. than it the pressure ot spring S were exerted substantially above or below'the central part ot ring l.. Further- Inore any tendency oit the ring' to twist is overcome and the upper 'tace or the ring is nrgfjed with an even bearing against the side lwall ot the piston groove.

The three rings are assembled in the circuni'lerential groove 9 ot the piston head l() in such position that Vthe lines ol division of the rings break joint. lllhen assembled in the `groove olf the piston head as shown in lligs. l, 2 and 23, the ring l fits the cylinder bore and is urged. into contact therewith by the follower ring S. The ring 8, cooperating ldd with the beveled surface 5 of the packing ring 1, by reason ot its expansion makes a constant bearing engagement with the beveled suriace. One component ot the torce being exerted against the beveled surface 5 tends to expand the ring 1 and thereby 'effect a 'tight closure between the periphery of the ring 1 and the cylinder wall; while the other component ot said torce tends to thrust said packing` ring bodily endwise with relation to the piston head 10 andthereby hold the tace of the ring 1 in tight engagement with one wall ot the groove 9. Thus the packing ring is maintained tight against loss oipressure both between the ring and the cylinder wall and underneath the ring between the ring and the piston groove.

rThe ring 6 serves to support the spring` ring 8 in the region ot the middle of ring 1, and also to prevent the ring 1 irom tipping inwardly away from contact with the cylinder wall when there is any tendency ot the ring to so tip under the influence of the follower ring 8. lWhen the ring G is given resiliency ot its own, it not only tultills this function but through its beveled face T wedges itselil between the beveled tace 5 ofthe packing yring 1 and the lower wall of the groove 9, thereby .niaintaining a gastight joint between the ring l and the lower wall of the piston groove 9.

'The modified form ot packing shown in Fig. L is substantially similar' to the packing shown in Figs. 1, 2 and 3, but differs therefrom in that the packing ring 11. is trapezitorm in cross-section .and` of less width than the groove9 ot the piston head. This torni has some advantage over the 'form hereinbetore. described in that the lower sharp edge of the ring is eliminated and the ring provided with a less pronounced.

bevel for the saine depth ot.' groove, i. e., the

beveled tace 12 more nearly parallel with the outer peripheral face 13 of the ring. By providing less bevel to the tace 12 the component oi force exerted by the follower ring 1.4i tending to urge the packing ring 11V against the cylinder wall is increased, and` the upward component tending to urge the ringgagainst the wall o'li the groove is decreased., thereby isnring a tighter joint between the ring and the cylinder. The spring follower ring 14 in this modification is shown flattened on both sides.

ln Fig. 5, i have shown a further modified form o packing in whichthe packing ring 15 is formed with an inner face having a lower portion 16 thereof parallel with the outer tace thereof, and an upper portion 1"? beveled at an obtuse angleto the lower portion ot the tare. The ring 18 which bears against the lower portion 1G of the inner face of the ring 15 is rectangular in cross-section and ot snhcient'height to snpport the `follower ring 19 substantially in the central region of the groove 9 where its expansive force will be applied against the beveled portion of the inner tace of ring 15 opposite the central regionl of the ring. The

ring 18 may or may not be made to exert an expansive pressure as desired; and the ring 19 as herein shown is iiat on one side only.

As shown in liig. 7 the cle'fts in the rings 15, 18 and 19 (and the corresponding clefts in the other modifications) are positioned substantially 90O from each other so that the rings are in broken joint relation to each other. They may be conveniently held in suoli relative positions by means of pins 2() andQl carried by the rings 15 and 18 respectively and adapted to be positioned in the clet'ts 9,2 and L3 respectively of the rings 19 and 18. By thus positioning the rings with their clefts breaking joints at substantially 90O trom each other, the packing ring 15 is forced outwardly with more nearly even pressure throughout its periphery and the tendency ot the ring to expand into an elliptical form, thereby wearing the bore of the cylinder unevenly, is overcome.

ln Fig. 6 I have illustrated several forms ot spring follower rings by cross-sectional views thereof. The forms shown at 24,. 25 and 26 are all made from round steel wire, the ring section 25 being made from wire ground or drawn flat on diametrically' opposite sides, and the ring section 26 being made t'rom wire ground or drawn Hat on one side, the fiat tace oit the ringbeing adapted to bear on the ring which supports it. The spring ring section 27 is triangular in outline and is beveled to correspond to lthe bevel ot the packing ring against which it applies its expansive force.

l claim: y

1. ln combination with a piston having an annular groove, a packingin said groove comprising a packing ring having a beveled inner tace, a Asecond ring resting on the bottom side oi. said groove, and a spring follower ring supported within said groove by said second ring and engaging the beveled tace ot the packing ring.

2. ln combination with a piston having an annular groove, a packing in said groove comprising a packing ring' having a beveled inner tace, a second ring resting on the bottom side ot said groove and having an outer beveled tace corresponding to the beveled tare ot. the packing ring, and a springl follower ring supported within said groovefby said second ring and engaging lthe beveled iace ot the packing ring.

3. ln combination with a piston having an annular groove. a packing in said groove comprising a packing ring having a beveled inner tace. a spring 'follower ring engaging said beveled tace, and a supporting ring resting on the bottom of the groove adapted to support the spring follower ring opposite the central region of the packing ring.

4. A composite piston packing for use in the cylinders of internal combustion engines comprising a ring of substantially righttriangular section having a surface engage- :ible with the cylinder Wall, a second ring.

of trapeziform cross-section having the inclined face thereof in engagement With that side of said first ring which constitutes the liypotenuse of its triangular section and means for expanding said first ring.

ln combination with a piston for use in an engine cylinder, said piston having an annular groove therein, a packing in said groove comprising a pair of rings, one of said rings extending substantially from one side wall of the groove to the other and having a surface for engagement with thesubstantially parallel to the side wall of the piston groove, and an expander ring arranged witliin said angle and being supported upon Said last named surface.

6. In combination with a piston for use in the cylinder of an internal combustion engine and having an annular groove therein, a piston ring of substantially triangular cross section having one side thereof in engagement With a side Wall of the piston groove, and having a second side of a Width substantially equal to that of the piston groove and constructed and arranged for engagement with a cylinder Wall, a second ring having a surface in engagement With the other side wall of the groove, said rings having other faces intersecting each other at an acute angle, and an expander ring resting upon one of such intersecting faces and engaging the other thereof.

Signed by me at Boston, Massachusetts, this lst day of August 1919.

LEWIS C. MARSHALL. 

